drivers/iio/kfifo_buf.c

   1 #include <linux/slab.h>
   2 #include <linux/kernel.h>
   3 #include <linux/module.h>
   4 #include <linux/device.h>
   5 #include <linux/workqueue.h>
   6 #include <linux/kfifo.h>
   7 #include <linux/mutex.h>
   8 #include <linux/iio/kfifo_buf.h>
   9 #include <linux/sched.h>
  10 #include <linux/poll.h>
  11
  12 struct iio_kfifo {
  13         struct iio_buffer buffer;
  14         struct kfifo kf;
  15         struct mutex user_lock;
  16         int update_needed;
  17 };
  18
  19 #define iio_to_kfifo(r) container_of(r, struct iio_kfifo, buffer)
  20
  21 static inline int __iio_allocate_kfifo(struct iio_kfifo *buf,
  22                                 int bytes_per_datum, int length)
  23 {
  24         if ((length == 0) || (bytes_per_datum == 0))
  25                 return -EINVAL;
  26
  27         return __kfifo_alloc((struct __kfifo *)&buf->kf, length,
  28                              bytes_per_datum, GFP_KERNEL);
  29 }
  30
  31 static int iio_request_update_kfifo(struct iio_buffer *r)
  32 {
  33         int ret = 0;
  34         struct iio_kfifo *buf = iio_to_kfifo(r);
  35
  36         mutex_lock(&buf->user_lock);
  37         if (buf->update_needed) {
  38                 kfifo_free(&buf->kf);
  39                 ret = __iio_allocate_kfifo(buf, buf->buffer.bytes_per_datum,
  40                                    buf->buffer.length);
  41                 buf->update_needed = false;
  42         } else {
  43                 kfifo_reset_out(&buf->kf);
  44         }
  45         r->stufftoread = false;
  46         mutex_unlock(&buf->user_lock);
  47
  48         return ret;
  49 }
  50
  51 static int iio_get_length_kfifo(struct iio_buffer *r)
  52 {
  53         return r->length;
  54 }
  55
  56 static IIO_BUFFER_ENABLE_ATTR;
  57 static IIO_BUFFER_LENGTH_ATTR;
  58
  59 static struct attribute *iio_kfifo_attributes[] = {
  60         &dev_attr_length.attr,
  61         &dev_attr_enable.attr,
  62         NULL,
  63 };
  64
  65 static struct attribute_group iio_kfifo_attribute_group = {
  66         .attrs = iio_kfifo_attributes,
  67         .name = "buffer",
  68 };
  69
  70 static int iio_get_bytes_per_datum_kfifo(struct iio_buffer *r)
  71 {
  72         return r->bytes_per_datum;
  73 }
  74
  75 static int iio_mark_update_needed_kfifo(struct iio_buffer *r)
  76 {
  77         struct iio_kfifo *kf = iio_to_kfifo(r);
  78         kf->update_needed = true;
  79         return 0;
  80 }
  81
  82 static int iio_set_bytes_per_datum_kfifo(struct iio_buffer *r, size_t bpd)
  83 {
  84         if (r->bytes_per_datum != bpd) {
  85                 r->bytes_per_datum = bpd;
  86                 iio_mark_update_needed_kfifo(r);
  87         }
  88         return 0;
  89 }
  90
  91 static int iio_set_length_kfifo(struct iio_buffer *r, int length)
  92 {
  93         /* Avoid an invalid state */
  94         if (length < 2)
  95                 length = 2;
  96         if (r->length != length) {
  97                 r->length = length;
  98                 iio_mark_update_needed_kfifo(r);
  99         }
 100         return 0;
 101 }
 102
 103 static int iio_store_to_kfifo(struct iio_buffer *r,
 104                               const void *data)
 105 {
 106         int ret;
 107         struct iio_kfifo *kf = iio_to_kfifo(r);
 108         ret = kfifo_in(&kf->kf, data, 1);
 109         if (ret != 1)
 110                 return -EBUSY;
 111         r->stufftoread = true;
 112         wake_up_interruptible_poll(&r->pollq, POLLIN | POLLRDNORM);
 113
 114         return 0;
 115 }
 116
 117 static int iio_read_first_n_kfifo(struct iio_buffer *r,
 118                            size_t n, char __user *buf)
 119 {
 120         int ret, copied;
 121         struct iio_kfifo *kf = iio_to_kfifo(r);
 122
 123         if (mutex_lock_interruptible(&kf->user_lock))
 124                 return -ERESTARTSYS;
 125
 126         if (!kfifo_initialized(&kf->kf) || n < kfifo_esize(&kf->kf))
 127                 ret = -EINVAL;
 128         else
 129                 ret = kfifo_to_user(&kf->kf, buf, n, &copied);
 130
 131         if (kfifo_is_empty(&kf->kf))
 132                 r->stufftoread = false;
 133         /* verify it is still empty to avoid race */
 134         if (!kfifo_is_empty(&kf->kf))
 135                 r->stufftoread = true;
 136
 137         mutex_unlock(&kf->user_lock);
 138         if (ret < 0)
 139                 return ret;
 140
 141         return copied;
 142 }
 143
 144 static void iio_kfifo_buffer_release(struct iio_buffer *buffer)
 145 {
 146         struct iio_kfifo *kf = iio_to_kfifo(buffer);
 147
 148         mutex_destroy(&kf->user_lock);
 149         kfifo_free(&kf->kf);
 150         kfree(kf);
 151 }
 152
 153 static const struct iio_buffer_access_funcs kfifo_access_funcs = {
 154         .store_to = &iio_store_to_kfifo,
 155         .read_first_n = &iio_read_first_n_kfifo,
 156         .request_update = &iio_request_update_kfifo,
 157         .get_bytes_per_datum = &iio_get_bytes_per_datum_kfifo,
 158         .set_bytes_per_datum = &iio_set_bytes_per_datum_kfifo,
 159         .get_length = &iio_get_length_kfifo,
 160         .set_length = &iio_set_length_kfifo,
 161         .release = &iio_kfifo_buffer_release,
 162 };
 163
 164 struct iio_buffer *iio_kfifo_allocate(struct iio_dev *indio_dev)
 165 {
 166         struct iio_kfifo *kf;
 167
 168         kf = kzalloc(sizeof *kf, GFP_KERNEL);
 169         if (!kf)
 170                 return NULL;
 171         kf->update_needed = true;
 172         iio_buffer_init(&kf->buffer);
 173         kf->buffer.attrs = &iio_kfifo_attribute_group;
 174         kf->buffer.access = &kfifo_access_funcs;
 175         kf->buffer.length = 2;
 176         mutex_init(&kf->user_lock);
 177         return &kf->buffer;
 178 }
 179 EXPORT_SYMBOL(iio_kfifo_allocate);
 180
 181 void iio_kfifo_free(struct iio_buffer *r)
 182 {
 183         iio_buffer_put(r);
 184 }
 185 EXPORT_SYMBOL(iio_kfifo_free);
 186
 187 MODULE_LICENSE("GPL");